CONOCARDTUM KONINCKI. 465 



Exterior. — In perfect examples the surface is almost smooth, covered with 

 concentric lines and striae of growth, crossed by fine radiating lines, which appear 

 collected into bundles, indicating the ribs seen in the inner plates of the shell ; 

 posteriorly, on the body of the valve, more or less well-marked but much-flattened 

 ribs appear. 



If the outer plate of shell be removed the shell is seen to be crossed by 

 radiating ribs, separated by broad furrows, especially well marked in the middle 

 portion of the anterior wing. These ribs appear to be scalariform. The posterior 

 surface is covered by excentric, fine, close ribs, exhibiting the same character 

 when their outer plate is absent. The rostrum is striated longitudinally. 



Dimensions. — PI. LIV, fig. 12, measures — 



Antero-posteriorly . . . .110 mm. 



Dorso-ventrally . . . .61 mm. 



From side to side . . . .61 mm. 



Length of rostrum . . . .40 mm. 



Localities. — Ireland: the Carboniferous Limestone of llathkeale and Nanteenan, 

 Bansha, co. Limerick. 



Observations. — Baily gave three fine figures of G. Konincld in his original 

 paper on this species (ojj). cit.), but I am unable to trace the figured specimens. 

 There is, however, a fine series of specimens in the collection of the Geological 

 Survey of Ireland at the Royal Museum of Science and Art, which I have been 

 permitted to study and to use for illustrations (PI. LIV, figs. 12 and 13). 

 Mr. Baily says that he recorded the name at the meeting of the British Associa- 

 tion at Dublin in 1865 ; but it appears that there was no description. It appears, 

 too, that the shell was recognised as a new species by de Koninck, who subse- 

 quently recognised that it occurred in Belgium. 



The peculiar characters of G. Konincld are the very large, globosely triangular 

 body, large umbones, and marked constriction between the body and the anterior 

 wing. In G.fusiforme this constriction is almost absent. The rostrum is pro- 

 duced backwards and slightly upwards — a character which distinguishes the shell 

 from G. aliforme, which has in addition a much more angular body, and a more 

 rapidly truncated posterior surface. The ribs which radiate from the umbo 

 between the layers of the shell are large and further apart than in other species. 

 At present I have not been able to satisfy myself that this species occurs in the 

 Carboniferous Limestone of England. Its presence has been noted, however, in 

 the limestones of Lancashire near Clitheroe (Davis and Lees, ' West Yorkshire,' 

 and Mr. R. Etheridge in the Geological Survey memoir on the Burnley coal-field). 

 I am disposed to think that G. Hiberiiicwm has been mistaken for G. Konincld in 

 these cases ; for the shells from Clitheroe certainly had a broad flange of shell 

 attached to the sharp external border of the valve posteriorly. 



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